Method for treatment of tow



Jan. 23, 1968 'r. c. FRITZ ETAL METHOD FOR TREATMENT OF TOW 4 Sheets-Sheet 1 Filed Dec. 11-, 1963 THEODORE C. FRITZ RICHARD F. DYER BY MM ATTORNEYS 1968 T. c. FRITZ ETAL 3,365,

METHOD FOR TREATMENT OF TOW I Filed Dec. 11, 1965 4 Sheets-Sheet 2 THEODORE C. F R/ 7'2 RICHARD F. DYE/P INVENTOR.

' ATTORNEYS BY QMM Jan. 23, 1968 T, c. FRITZ ETAL METHOD FOR TREATMENT OF TOW 4 Sheets-Sheet 3 Filed Dec. 11. 1963 THEODORE C. FRITZ R/C'HARD F. 075/? ATTORNEYS 1968 T. c. FRITZ ETAL 3,365,346 METHODRFOR TREATMENT OF Tow Filed Dec. 11, 1963 4 Sheets-Sheet 4 THEODORE 'Cl FRITZ RICHARD F, OVER INVENTOR.

Patented Jan. 23, 1968 3,365,346 METHOD FOR TREATMENT OF TOW Theodore Calvin Fritz and Richard Fairbanks Dyer,

Kingsport, Tenn, assignors t Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Filed Dec. 11, 1963, Ser. No. 329,763 Claims.(Cl. 156--152) This invention relates to a method for applying additives to continuous filament tow. More particularly, it relates to a method for applying additives to tow adapted for producing rod-like elements useful in the manufacture of tobacco smoke filters.

The selectivity of filtration of tobacco smoke filter elements may often be improved by adding certain materials to the continuous filament tow prior to its compaction into the form of filter rods. The addition of these materials imparts an increased afiinity for certain components of the tobacco smoke which may be displeasing to the smoker. Some of the additives which have been used for this purpose are disclosed by our coworkers in U .8. Patents 2,881,769, 2,940,456, 2,956,329, 3,008,472, 3,008,473 and 3,062,611. Representative of methods which may be used to apply such additives to filter tow are those disclosed by our coworker Touey in U.S. 3,043,736, for example, applying in conjunction with a volatile organic vehicle or plasticizer for the filaments of the tow, blowing onto the filaments in particulate form and spraying as a powder onto filaments wet with an adhesivve or plasticizer. In US. 2,881,770, Touey includes a method of applying powder to fibers electrostatically, i.e., by inducing a charge on the fibers by friction or other suitable means and then running the fibers through a chamber containing a highly concentrated dust. Although these methods have proved highly successful, it is apparent that development of a further system for applying such additives such that they are readily taken up by the tow and penetrate sufiiciently to induce the required filterability and removal characteristics to the filter rods in which the tow containing same is used represents a highly desirable result. After extended investigation we have devised such a method for applying filter-improving additives to continuous filament tow.

One object of this invention is to provide method for applying additives to continuous filament tow. Another object of this invention is to provide a way for adding to filament-filter tow materials which improves the efficiency of filter elements in which said tow is used. Further objects will appear hereinafter.

In its broader aspects our invention involves applying additive to continuous filament tow from a liquid bath containing a colloidal suspension, emulsion, solution or slurry of the additive. In one embodiment of our invention, the tow is passe-d through the nip formed between two rolls, the lower of which rotates counterclockwise in the liquid bath. In an alternate embodiment, the tow passes first into the liquid bath, then under a roll rotating clockwise in said bath and next, after leaving said liquid bath, through the nip formed between two rolls, the lower of which may be partially immersed in said liquid bath. Our invention further includes additive application in conjunction with drying the tow to remove liquid therefrom thus implementing the penetration of additive therein.

For assistance in a better understanding of the invention, reference is made to the attached drawing forming a part of the instant application.

FIG. 1 is a schematic drawing in flow sheet form depicting the tow treatment from supply of tow to preparation of first plug or filter element product, including additive application stage.

FIG. 2 is a perspective View showing tow treatment from the time of removal from tow source to introduction to garniture and filter forming means. Application of additive is shown in greater detail in the enlargement of FIG. 5.

FIG. 3 is a perspective view again showing treatment of the tow from removal of tow from tow source to introduction to garniture and forming means, in this instance depicting an alternate form of the additive applying and tow drying stages.

FIG. 4 is a perspective view likewise showing treatment of the tow from the step of removal from bale to the step of introduction to garniture, in this instance depicting a further embodiment of the tow drying step and. an alte nate feed roll system comprising pretensioning rolls.

FIG. 5 is an enlargement view of the additive applying step shown in FIG. 2.

FIG. 6 is an enlargement View of the additive applying embodiment shown in FIG. 3.

In FIG. 1 the tow is shown in flow sheet form passing through the following stages from supply of tow to formation of product: banding and spreading, additive application, drying, blooming and plug making, tow feed steps being included between each of the major tow treatment steps.

Turning now to FIG. 2, a crimped multifilament tow 10 is withdrawn from the supply bale 12 through a banding jet 14 such as described in Jackson 2,737,688 or Dyer et al. 3,081,951, over a stationary or rotatable cylindrical guide 16. If desired, the tow may be subjected to a further banding and spreading operation in jet 18 to insure uniform filament distribution across the width of the tow. The tow then is passed between positively driven roll pair 20 and 22. These rolls are forced into a positive nip or bite with each other by suitable fiuid diaphragm or mechanical loading means 24 and 26 such as are thought to be well known in the art and needing no further description herewith. The surfaces of rolls 20 and 22 may be of stainless steel or other non-corrosive metal or one roll may have a metallic surface and the other may be covered with a cylindrical rubber sleeve of suitable chemical resistance and hardness. If desired, both rolls may be rubber covered, or in the alternative a standard cold or hot rolled steel roll or rolls with a chemical-resistant and stick-resistant coating of Teflon or other suitable plastic may be used. Good results have been obtained when top roll 20 is rubber covered and bottom roll 22 is stainless steel. Bottom roll 22 is immersed in a liquid filled trough 28. Additive-containing fluid 30 may be delivered to the trough 28 through feed line 32 by constant volume pump 34 connected to supply tank 36 of liquid additive material by supply line 38. A simple gravity overflow line 40 is provided to maintain a constant liquid level in the trough 28 and return any excess material to the supply tank or pump through return line 40,

Bottom roll 22 rotates counterclockwise to pick up a coating of the additive material 30 and apply it to the tow 10 as the tow enters the nip or rolls 20 and 22. The pressure nip of rolls 2%? and 22 serves to squeeze out the eXcess of additive to the desired level of pickup, squeeze and work the additive into and throughout the thickness of the filamentary tow mass to achieve uniform distribution of the additive on all filaments.

In some cases it may also be desirable to form additional crimp in the tow filaments at this point. This may be readily done by providing at least one of the rolls 20 and 22 or both with a resilient compressible rubber covering. When the rolls are pressed toward each other under force in excess of 100 to 1000 pounds per linear unit of roll length, the resilient rubber roll surfaces are deformed and the decrease in the linear speed of the roll surface in the center of the nip causes filament buckling and crimping. This crimping effect is particularly enhanced if the liquid carrier for the additive is a softening agent such as water in the case of cellulose ester tows or an appropriate plasticizer or partial solvent.

After emerging from the nip of rolls 20 and 22 the tow is laid in a substantially tensionless manner on an endless conveyor belt 42. This belt may be of a non-corrosive, highly porous structure such as fiexible open-mesh stainless-steel wire or Teflon-coated light-weight link-chain belting. Conveyor belt 42 carries the tow in a relaxed tensionless state between heat sources 44 and 46 disposed respectively over and beneath conveyor belt 42. These heat sources may be infrared electric heaters, gas heaters, steam lines or hot air ducts as desired. In this zone the liquid carrier is evaporated and any chemical binder present in the additive mixture is cured either partially or completely to band the additive material to the tow filaments.

The tow is then removed from conveyor belt 42 by feed roll pairs 48 and 50 and S2 and 54 and passed directly to trumpet or staffer jet 56 and then to the plug maker 58. For good results a common drive for rolls 20 and 22, conveyor belt 42, feed rolls 43, 50, 52 and 54 and plug maker 58 as well as additive pump 34 may be provided, with suitable means for adjusting or changing the speed ratio between the various driven components. It has also been found economical to subject the tow to a filament fiufiing or blooming operation such as described in aforementioned US. Patents 2,794,239 and 3,079,663.

In FIG. 3 substantially the same steps as shown in FIG. 2 are included with the exception that an alternate form for applying the additive from the liquid bath is shown, as is also an alternate form for drying the tow after application of additive. In this instance, tow 10 passes under roll 60 immersed in the liquid bath and then passes between the nip formed by rolls 20 and 22, excess additive being removed by so passing between this nip. Next the tow passes alternately over and under a plurality of upper 62 and lower 64 drying heated drums or rolls. The upper rolls 62 are slightly offset from the lower rolls 64 just sufficiently to allow passage of tow around about twothirds of the surface of each roll. The additive application step of this embodiment may be seen in further detail in the enlargement shown in FIG. 6.

Referring now to FIG. 4 tension is applied to the tow 10 by passage between pretension rolls 66 and 68 prior to passage between feed rolls 70 and 72. In the tow drying step of this embodiment tow is passed through a box-like oven portion 74 in which it is passed respectively from top to bottom over endless belts 76, 78, S0, 82 and 84 positioned one above another, moving first downstream and then upstream in the reverse direction until it leaves endles belt 82 and moves out of dryer 74, between rolls 52 and 54 and into stuffer jet 56 and garniture or plug maker 58.

In our invention where a suspension of additive is applied a binder material such as polyvinyl alcohol or acetate or a cooked starch may be advantageously used to bond the additive particles to the filaments and also to aid in providing the desired rod firmness in final fiter.

Example I A denier per filament (d./f.)/80,000 total denier (I D) regular cross section cellulose acetate tow with webby interlace was treated in a set up such as that shown in FIG. 2 of the drawing using a liquid bath of 35% solids of activated charcoal in water. The following table gives the conditions of the run and the properties of filter rods made from this tow. The acetaldehyde, isoprene and tar removal values in this and the following examples were measured by smoking king size (85 mm.) cigarettes of a standard brand available on the retail market in the US. shortened by 13 mm. and with 13 mm. filter rods affixed thereto on a smoking machine similar in design and operation to the smoking machine described by J. A. Bradford, W. R. Harlan and H. R. Hammer in Industrial and Engineering Chemistry, vol. 28, pp. 836-9 (1936).

Roll: Factors Tape roll speed f.p.m. 137 Feed roll speed f.p.m 136 Delivery roll speed f.p.m 137 Applicator roll speed f.p.m 113 Feed roll pressure p.s.i.g. 25 Circumference of rod mm. 24.7 Rod length mm 102 Pressure drop absolute inches 12.8 Hardness 9.8 Individual weight grams 1.495 Percent charcoal applied (50 p.p.h.

percent 33.6 Temperature on dryer, C. 200 Acetaldehyde removed on 3rd puff pcrcent 92 Isoprene removed on 3rd puff percent 92 1 Feet per minute.

Pounds per square inch gauge. 3 Millimeters.

4 Parts per hundred.

Example II A 5 d./f./80,000 TD reguiar cross section cellulose acetate tow with webby interlace was treated in a set up similar to that described in FIG. 2 of the drawing using a liquid bath of 25% solids of activated charcoal in water. The following table presents conditions and results.

Roll: Factors Tape roll speed f.p.m 101 Feed roll speed f.p.m 96 Delivery roll speed f.p.rn 101 Applicator roll s eed f.p.m 83 Feed roll pressure p.s.i.g 50 Circumference of rod mm 24.8 Rod length mm 102 Pressure drop ABS inches 14.7 Hardness 13.0 Individual weights grams 1.350 Percent charcoal applied (37 p.p.h.)

percent.- 27 Temperature on dryer C 200 Acetaldehyde removal on 3rd puif per-cent 92-91 Isoprene removed on 3rd puff do 79-85 Tar removal do 40 Example III The procedure of Example I was followed with a rice starch liquid bath being substituted for the charcoal bath. Following are the conditions and results of operation.

Example V A comparison was made by using equivalent tobacco smoke filter rods made from 5 d./f. 80,000 TD cellulose acetate tow, but without additive and testing for acetaldehyde and isoprene removal. Following are the results.

Percent Acetaldehyde removal on 3rd puff 0 Isoprene removal on 3rd puif 6 Tar removal a 23 A further comparison was made by testing a commercially available paper filter rod treated with activated charcoal. The smoking test results were as follows:

Percent Acetaldehyde removal on 3rd puff 70 Isoprene removal on 3rd puff 80 These results demonstrate the utility and efficiency of the tow treatment process of this invention.

Example V A regenerated cellulose tow such as that of Touey patent application U.S. Ser. No. 185,824, filed April 9, 1962 and now abandoned, was treated as in Example I. The properties of filter rods prepared from this tow were comparable to those of Example I.

Example VI A polyethylene tow such as that of US. Patent 2,966,- 157 was treated according to the procedure of Example I and then formed into filter rods. The pressure drop and tow removal of the rods proved satisfactory upon subjection to smoking tests as in Examples I-III.

Example VII The procedure of Example I was followed except that rice starch was used as the additive and the tow treated consisted of a styrene polymer tow such as that disclosed in Touey patent application U.S. Ser. No. 279,777, filed May 13, 1963 and now abandoned. Properties of filter rods prepared from this tow compared favorably to those of the rods of Example III.

Example VIII The procedure of Example I was followed in applying in place of activated charcoal in water the following composition.

Percent Barnebey-Cheney, Type 495, activated carbon 26.0 Methocel, MC, USP, c.p.s. (methyl cellulose) 2.0 lvanol, 51-05 (polyvinyl alcohol) 5.0 Water 67.0

Example IX The composition of Example VIII was applied to filter tow according to the process of Example I except that rice starch was used in place of carbon black.

Example X Example XI A series of 20 test samples were made using 8 d./f. 64,000 TD cellulose acetate tow or 8 d./f. 48,000 TD tow. The process of FIGURE 2 was used. A water slurry containing 27% of a 325 mesh or finer activated carbon and 5% methyl cellulose, 10 c.p.s. viscosity, binder and 68% water was used. The rods were tested for tar removal in comparison with controls of similar rod weight containing no carbon. Table I summarizes these results. It may be seen that the rods containing finely divided activated carbon exhibited a substantially higher tar removal. Use of 150 mesh or coarser carbon particles failed to give a comparable higher tar removal.

TABLE I mm. Rod Weights 17 mm. DJL/TD Tip Sample in Removal,

Thousands Rod, Acetate, Additive, Percent mg. mg. mg. Tats From the foregoing description and examples it is thought apparent we have provided method and apparatus highly useful in treating tow to improve filter removal and the like properties thereof.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

We claim:

1. A process for the production of tobacco smoke filter elements which comprises withdrawing crimped m-ulti-filament tow from a tow source, banding said tow to a substantially uniform filament distribution across the width of said tow, passing the tow next in contact with a driven roll, said roll being at least partially immersed in a liquid bath of additive, said additive being applied to the surface of said tow as it passes in contact therewith, working additive into said tow to a substantially uniform distribution and removing any excess additive therefrom, next drying the treated tow, thereby removing any liquid therefrom, and, after blooming said tow, compacting the additive-containing tow into the form of tobacco smoke filter elements.

2. The process according to claim 1 wherein the drying is accomplished by conducting the tow in a relaxed tensionless state between heat sources deposed respectively over and beneath said tow as it passes therebetween.

3. The process according to claim 1 wherein the drying is accomplished by conducting the tow in a relaxed tensionless state circuitously over and around a plurality of adjacent heated rotating elements.

4. The process according to claim 1 wherein the tow is passed between a rotating roll pair one of which is the said partially immersed roll.

7 8 5. The process according to claim 1 wherein the tow 3,043,736 7/1962 Touey 156152 is passed under the said immersed roll and into the liquid 3,098,370 7/1963 Poole et a1. 117-111 X bath, and is thereafter directed through a roll pair to 3,099,594 7/1963 Caines et a1. 156-152 uniformly distribute and remove excess additive. 3,161,557 12/1964 Muller 156-462 3 5 3,244,544 4/1966 Scharf 117-111 X References Cited Primary Examiner.

2,381,772 4/1959 Touey et a1 131-403 MELVIN D. REIN, Examiner- 9 9 9/ 1959 Kiefer \131208 M. L. KATZ, Assistant Examiner,

3,019,130 1/1962 Hornbostel 117111 10 

1. A PROCESS FOR THE PRODUCTION OF TOBACCO SMOKE FILTER ELEMENTS WHICH COMPRISES WITHDRAWING CRIMPED MULTI-FILAMENT TOW FROM A TOW SOURCE, BANDING SAID TOW TO A SUBSTANTIALLY UNIFORM FILAMENT DISTRIBUTION ACROSS THE WIDTH OF SAID TOW, PASSING THE TOW NEXT IN CONTACT WITH A DRIVEN ROLL, SAID ROLL BEING AT LEAST PARTIALLY IMMERSED IN A LIQUID BATH OF ADDITIVE, SAID ADDITIVE BEING APPLIED TO THE SURFACE OF SAID TOW AS IT PASSES IN CONTACT THEREWITH, WORKING ADDITIVE INTO SAID TOW TO A SUBSTANTIALLY UNIFORM DISTRIBUTION AND REMOVING ANY EXCESS ADDITIVE THEREFROM, NEXT DRYING THE TREATED TOW, THEREBY REMOVING ANY LIQUID THEREFROM, AND, AFTER BLOOMING SAID TOW, COMPACTING THE ADDITIVE-CONTAINING TOW INTO THE FORM OF TOBACCO SMOKE FILTER ELEMENTS. 